Ortho dialkyl benzene preparation via dehydrocyclization process

ABSTRACT

Salts of orthodialkyl benzene sulfonates have been disclosed as having excellent detersive and biode-gradability properties. A process for manufacturing these compounds has also been disclosed. In this process, paraffinic stock of certain carbon atom range is reacted with the aid of a dehydrocyclization catalyst to produce the dialkyl benzene precursors.

United States Patent [191 De Gramontet al.

[ 1 ORTHO DIALKYL BENZENE PREPARATION VIA DEHYDROCYCLIZATION PROCESS[75] Inventors: Arnaud Marie Jose De Gramont,

Bougival; Jean Maurin, Montivilliers; Joseph Edouard Weisang, Le Havre,all of France [73] Assignee: Compagnie F rancaise De Raffinage,

Paris, France [22] Filed: Mar. 24, 1970 [21] Appl. No.: 22,337

[30] Foreign Application Priority Data Mar. 26, 1969 France 6908911 [52]US. Cl. 260/673.5, 260/505 S [51] Int. Cl. C070 5/22 [58] Field ofSearch 260/505 S, 505 A, 260/6735 [56] 5 References Cited UNITED STATESPATENTS 3,360,586 12/1967 Block et a1 260/6833 3.291.755 12/1966 Haenselet al. 252/464 2.962.536 11/1960 Pitts 260/6735 2.321.006 6/1943 Burk etal. 260/668 Sept. 25, 11973 OTHER PUBLICATIONS J. L. Ernst, The Oil andGas Journal, 64, 112-115 (1966).

Primary ExaminerLeon Zitver Assistant Examiner-Leo B. DeCrescenteAtt0rneyCurtis, Morris and Safford [57] ABSTRACT Salts of orthodialkylbenzene sulfonates have been disclosed as having excellent detersive andbiode-gradability properties. A process for manufacturing thesecompounds has also been disclosed. In this process, paraffinic stock ofcertain carbon atom range is reacted with the aid ofa dehydrocyclizationcatalyst to produce the dialkyl benzene precursors.

1 Claim, 1 Drawing Figure ORTHO DIAL KYL BENZENE PREPARATION VIADEHYDROCYCLIZATION PROCESS This invention relates to compositions havingbiodegradable detergent properties, more particularly this inventionpertains to compositions consisting primarily of orthodialkylbenzenesulfonates having straight saturated hydrocarbon chains; further, theinvention also relates to an economical process of obtaining thesecompositions.

The detergent industry manufactures a large variety of'products whichfind numerous applications.

The most commonly used detergents are of an ionic nature. Onedistinguishes between alkyl sulfates, which are of limited use due totheir liquid state, and alkyl sulfonates and alkyl benzene sulfonates,which are in solid form and are of much wider use. The largest number ofdetergents is represented at the present time by the alkyl benzenesulfonates which are prepared by alkylation of aromatic hydrocarbons,primarily benzene, by chlorinated paraffins or olefins. The industry istherefore tending to produce more and more straight-chain alkyl benzenesulfates without any tertiary carbon, but isomerization of the alkylradical is difficult to avoid.

A number of processes have been used which have employed, as startingmaterials, paraffinic refinery stocks. For the; most part, theseprocesses have been based on stocks having a carbon atom range of up to10. However, these dehydrocyclization processes have not produced thestarting materials which could be sulfonated directly to producedetergent base stocks or produce a stock yielding the desired propertiesand/or biodegradability.

The main difficulty to be overcome in the production of thestraight-chain alkyl benzene sulfonates is therefore of an economicnature; to achieve sufficient biodegradability, it is necessary toeliminate from among the isomers obtained by alkylation those in whichthe hydrocarbon chain is not strictly linear.

The present invention solves the problem of the production ofstraight-chain alkyl benzene sulfonates and makes it possible to producethem under economic conditions, i.e., substantially only the normal orstraight-chain dialkyl benzenes are obtained.

One object ofthe present invention is to provide iridustry with newdetergents which can be preparedby an economical process.

Another object of the invention is to provide new biodegradabledetergents.

Still another object of the invention is to propose a method which makesit possible to produce such detergents easily and at low cost.

The purpose of the invention is compositions having bon orthodialkylbenzene sulfonates by a new process which assures very satisfactoryselectivity and yield.

Therefore, another object of the invention is an economical process ofmanufacturing compositions having biodegradable, detergent properties,said method being characterized by subjecting normal-paraffinhydrocarbons having a number of carbon atoms of between 14 and 24,terminal atoms included, to passage in a reactor or furnace in thepresence of hydrogen over a nonisomerizing cyclicizing dehydrogenationcatalyst; isolating the single-ring aromatic products obtained;sulfonating them; and neutralizing the resultant sulfonic acids by meansof a base.

The normal-paraffin hydrocarbons which serve as starting products can beobtained by passing a distillation stream or cut rich in normalparaffins over a molecular sieve.

The nonisomerizing cyclicizing dehydrogenation reaction can be carriedout in the presence of hydrogen; upon entrance into the reactor, themolar ratio of hydrogen to normal-paraffin hydrocarbons is between 0.1

v and 10. The temperature therein is within the range of 350C 500C; thetemperature depends on the catalyst used and will be given hereafter.During the dehydrogenation, there is a formation of normal olefins, acertain amount of diolefins and aromatic products.

The catalyst must be a nonisomerizing cyclicizing dehydrogenationcatalyst. As a catalyst, Pt-Li-As on alumina support is a suitablecomposition. Other, suitable and inert supports may be employed with thedisclosed catalysts.

The single-ring dialkyl aromatic hydrocarbons formed may be extracted inthe condensed fraction by suitable means, for instance by passagethrough molecular sieves, by adsorption over alumina or silica gel or byliquid-liquid extraction by means of a selective solvent.

It has been observed that the single-ring aromatic fraction collected iscomposed practically exclusively of saturated straight-chainorthodialkyl benzenes the sum of the number of carbon atoms in thedialkyl chains of which is between 8 and 18, terminal atoms included,when the initial normal paraffin has a number of carbon atoms of between14 and 24, terminal carbon atoms included.

The aromatic fraction is subjected to a sulfonation which may be carriedout with sulfuric anhydride (S0 diluted in an inert gas such asnitrogen.

The sulfonic acids obtained are then neutralized by a base, for instancesoda or ammonia. The resultant sulfonates are then dried.

Tests carried out have proven that the compositions thus obtainedsurprisingly have remarkable properties of detergency andbiodegradability.

The products of the invention comprise a group of compositions formedprimarily of orthodialkyl benzene sulfonates the hydrocarbon chains ofwhich are saturated and straight and which may be represented by thefollowing formula:

in which:

is the benzene ring M is an alkaline metal or the ammonium ion R and Rare two straight, saturated hydrocarbon chains without any tertiarycarbon atom. The sum of the numbers of carbon atoms contained in R and Ris equal to n6; n is the number of carbon atoms which the initial normalparaffin contains; n is between 14 and 24, terminal atoms included.

The accompanying drawing is a diagram which illustrates the twoprincipal stages of the process of the invention, namely thedehydrocyclization of a normal paraffin and the extraction of theorthodialkyl benzenes.

In this embodiment, a fresh normal paraffin having a number of carbonatoms of between 16 and 20, terminal carbon atoms included, whicharrives through the line 1 is mixed with recycled products consistingessentially of paraffins and olefins coming from the line 2. Thismixture is diluted with hydrogen coming from the line 3 in such a mannerthat the molar ratio of hydrogen to the normal-paraffin hydrocarbons isclose to one. The mixture obtained is introduced at the top of avertical reactor 4 brought to a temperature of between about 350C and450C. The reactor contains a catalyst consisting of chromium oxide andpotassium oxide deposited on alumina in proportions by weight, measuredwith respect to the alumina, of 2.5 percent for the chromium and 2.2percent for the potassium. The rate of flow of the normal paraffinmeasured per unit of reactor volume per hour (v/v/hr) is between 0.5 and2.5. The products of the dehydrocyclization reaction are recovered in areceiver 5 where the separation of the gases and the liquids takesplace. The gases which are composed primarily of hydrogen and crackingproducts are evacuated through the line 6; the liquids through the line7 arrive at an extraction column-8 which is filled, for instance, withsilica gel. Elution with npentane introduced through the line 9 makes itpossible to collect via the line 11 the paraffins and olefins which maybe recycled; such as, by feeding these to reactor 4 via line 2; furtherelution with ethyl ether introduced via line makes it possible torecover the aromatic products via the line 12. The latter consistpractically entirely of orthodialkyl benzenes with straight saturatedhydrocarbon chains the total of the numbers of carbon atoms of which isbetween 10 and 14, terminal carbon atoms included, depending upon thenormal paraffin initially introduced.

The sulfonation and then the neutralization are carried out inaccordance with the methods described above.

The invention is furthermore illustrated by the following examples,which are not of a limitative nature.

EXAMPLE I A stream of normal hexadecane and hydrogen is passed for 6hours over a dehydrogenation catalyst consisting of chromium oxide andpotassium oxide deposited on alumina, the chromium content being 2.5percent by weight and the potassium content 2.2 percent by weight, bothmeasured with respect to the alumina. The temperature is maintained at425C. The rate of flow of the hexadecane is 2 v/v/hr and the molar ratioof hexadecane to hydrogen is 1.

758.6 grams of condensed products are collected from the outlet of thereactor and absorbed on a column which has been previously filled withsilica gel. By elution with n-pentane, there are collected 735.5 gramsof a mixture composed of 89.5 percent by weight hexadecane and 10.5percent by weight olefins. By elution with ethyl ether, there arecollected 23.10 grams of aromatic products formed practically entirelyof C orthodialkyl benzenes having straight saturated hydrocarbon chainsfor which the sum of the numbers of carbon atoms is 10.

These aromatic products are diluted in normal undecane in such a mannerthat the concentration by weight of the aromatic products is equal to15.15 percent. Into this solution which is maintained at 20C there isintroduced a stream of gaseous sulfuric anhydride (S0 diluted innitrogen in such a manner that the molar concentration of the sulfuricanhydride is equal to 3 percent. The stream of gas is maintained for 2hours; thus, the molar ratio of the sulfuric anhydride used to theorthodialkyl benzenes is 1.2.

The product is neutralized while cold and then decanted. The aqueousphase is treated under reflux with an excess of soda for 1 hour. Theorganic phase is treated in the same manner with an excess of soda underpressure at 160C for 1 hour. The two aqueous phases are combined, theexcess of soda is neutralized with sulfuric acid and thereuponevaporated until obtaining a dry product which is composed primarily ofC sodium orthodialkyl benzene sulfonates the hydrocarbon chains of whichare straight and saturated.

The detergent properties of the product obtained were compared withthose of a current commercial soap by means of the following test. Thecurrent commercial soap is of the following composition: sodium salts offatty acids.

With the product of the invention there was prepared a wash powderhaving the following composition:

20 percent by weight pure detergent product to be tested;

- 18 percent sodium pyrophosphate;

- 5 percent sodium perborate;

4 percent colloidal Mg silicate;

9 percent anhydrous sodium carbonate;

43 percent anhydrous sodium sulfate;

1 percent carboxy methyl cellulose.

With this powder two aqueous solutions were prepared, one of 5 g/l ofpure detergent and the other of 2 g/l.

With this solution, washings of a fabric impregnated with a standardsoiling (fabric marketed under the name Cotton Soil Test Cloth 51 S 47")were carried out in a Launderometer" under the following conditions:washing of a sample of 5 g of fabric in 2 liters of solution for 30minutes at C with agitation with 10 stainless steel balls of about 6 mmin diameter.

In order to determine the detergent power, reflection measurements werecarried out by means of an apparatus marketed under the name Photovoltby the Photovol Corporation.

Using the green filter, the following luminances Y were determined:

Ye: luminance of the fabric after washing Ys: luminance of the fabricimpregnated with the standard dirt Yr: luminance of the support fabricnot impregnated with the standard dirt The detergent power wascalculated by means of the following formula:

DP in percent Ye Ys)/(Yt Y3 x 100 The luminances Ys and Y; for thefabric used were as follows:

TABLE I Detergent power Detergent power in a concentrain a concentrationof 2 g/l tion of 5 g/l Sodium orthodialkyl 22.6% 24.2% benzene sulfonateCurrent commercial 17.7% 20.1%

soap* Sodium Salts of fatty acids These washing tests show theremarkable detergent properties of the compositions of the invention.

The biodegradable properties of the orthodialkyl benzene sulfonatesprepared in the test described above have been determined in thefollowing manner:

For 7 days a microorganism culture was prepared with constant aerationat a temperature of 25C in a semisynthetic medium containing 20 mg permil of the product to be tested; thereupon at the end of this time, thesame quantity of detergent was again introduced and the test continueduntil the th day. On the 7th and 10th days, analyses were made so as tonote the elimination of the products and thus their biodegradability.

The culture broth used in the tests comprises between 2 and 4 X 10microorganisma per mm. It was prepared by aerobic fermentation in anutrient medium rich in microorganisms taken from the water of the SeineRiver at the point of discharge of the large sewer of Clichy in Paris.

The detergent content of the cultures of microorganisms is determined inaccordance with the method of Longwell and Maniece, the principle ofwhich is as follows: acolored complex is formed with methylene blue; itis extracted with chloroform and a colorimetric measurement made bycomparison with a standard product.

The biodegradation rate T at the end of 7 days is given by the followingformula:

T (C C, )X l00)/20 in which C is the detergent content in the testmedium on the 7th day, expressed in mg per mi], and C, is the detergentcontent in a control medium on the 7th day, expressed in mg per mil.

in similar manner, the biodegradation rate at the end of 10 days, T isgiven by the following formula:

T10 ato CH0) X 0 in which C is the detergent content in the test mediumon the 10th day, expressed in mg per mil, and C, the detergent contentin the control medium on the 10th day, expressed in mg per mil.

Finally, the actual biodegradability rate 7 is given by the followingformula:

T= (0.5 T, T )/1.5

The results obtained are set forth in Table 11.

TABLE II CONTROL Sample No. 17

Test Test No. 1 No. 2 Concentration of detergent 7th day (ppm) 0.80 3.653.9 Biodegradation 7th day 857 84.5 Concentration of detergent 10th day0.65 4.4 3.45 Biodegradation 10th day 90.6 93 Biodegradability 8 8.990.1 AVERAGE 89.5

EXAMPLE 11 The paraffins and olefins coming from the line 111 in theaccompanying diagram were passed over the catalyst described in ExampleI and mixed via line 2 with 33.5 grams of fresh n-hexadecane, namely atotal of 169.0 grams of paraffin-olefin mixture passing into the reactorafter mixture with hydrogen. The rate of flow of the total charge is 2v/v/hr, the temperature is 425C and the molar ratio of hydrogen tohydrocarbon is 1; the time of passage is 1 hour.

There are collected 759.0 grams of liquid products which are adsorbed ona column previously filled with silica gel.

By elution with n-pentane there are collected 717.3 grams of a mixturecomposed of 86.3 percent paraftins and 13.7 percent olefins by weight.By elution with ethyl ether there are collected 41.7 grams of productscomposed primarily of straight-chain C orthodialkyl benzenes.

These products are sulfonated and then neutralized in the mannerdescribed in Example 1. After drying there is obtained a mixturecontaining primarily C sodium orthodialkyl benzene sulfonates withsaturated straight hydrocarbon chains, the detergent and biodegradableproportions of which are comparable to those of the compositions ofExample 1.

EXAMPLE 111 A stream of normal hexadecane and hydrogen is passed for onehour over the catalyst used in Example 1, heated to 440C. The rate offlow of the normal hexadecane is maintained equal to g/hr, the v/v/hr ofthe normal hexadecane is established at 1.0. The rate of flow ofhydrogen is 10.6 liters per hour.

The sum of the weights of the cracking products, the dehydrogenationhydrogen and the carbon formed represents 1.4 gram.

The treatment described in Example I applied to the liquid phaseproduces 75.0 grams of normal hexadecane, 13.6 grams of olefins and 10grams of aromatic products very rich in C orthodialkyl benzenes withstraight saturated hydrocarbon chains.

These aromatic products are sulfonated by the method set forth inExample l;'the molar ratio of the sulfuric anhydride fixed to theorthodialkyl benzene is 1.133.

The sulfonic acids are neutralized by the method described in Example 1.

After drying, the mixture contains primarily C sodium orthodialkylbenzene sulfonates with saturated straight hydrocarbon chains; themixture has good detergent and biodegradable properties.

EXAMPLE IV A stream of n-hexadecane and hydrogen is passed for 2 hoursover a dehydrogenation catalyst composed of chromium, copper andpotassium on alumina, these metals having been deposited in the form ofnitrates, so that after calcination at 800C there is 4.97 percent byweight chromium, 3.03 percent copper and 1 percent potassium, measuredwith respect to the alumina. The temperature is maintained at 425C; therate of flow of hexadecane is l v/v/hr and the molar ratio of hydrogento hexadecane is 1.

For 100 grams of hexadecane introduced there are collected 12.9 g ofolefins, 9.8 g of aromatics, including 6.2 g of orthodialkyl benzenes,and 73.7 grams of unconverted hexadecane. During the dehydrogenationthere is no structural isomerization.

The orthodialkyl benzenes obtained are then separated and treated in themanner described in Example I to give C sodium orthodialkyl benzenesulfonates with saturated straight hydrocarbon chains having detergencyand biodegradability properties comparable to those of the compositionsof Example I.

EXAMPLE V A mixture of n-hexadecane and hydrogen is passed for 2 hoursover a catalyst consisting of platinum deposited on alumina. Thecatalyst comprises 0.75 percent by platinum, referred to the alumina,and also 0.5 percent lithium and 0.09 percent arsenic. The temperaturebeing maintained at 400C, the rate of flow of the hexadecane being 1v/v/hr, and the molar ratio of hydrogen to hexadecane being 1.0, thereare collected for grams of n-hexadecane introduced 69.0 grams ofunconverted hexadecane, 12 grams of aromatics, including 7.4 grams oforthodialkyl benzenes, and 12.6 grams of olefins. During thedehydrogenating reaction there is not noted any structural isomerizationof the olefin and the alkyl benzenes recovered have only straightchains.

These orthoalkyl benzenes are then sulfonated and neutralized in themanner described in the preceding examples in order to give thedetergent compositions according to the invention.

We claim:

1. A process for preparing ortho-dialkyl benzenes which comprises:

a. passing a stream consisting of normal paraffln hydrocarbons havingfrom 14 to 24 carbon atoms, together with from 0.1 to 10 mols ofhydrogen per mol of normal paraffin, into a reaction zone in thepresence of a supported, non-isomerizing, cyclicizing dehydrogenationcatalyst selected from the group consisting of l chromium oxide andpotassium oxide on alumina, and (2) the product produced by thecalcination of the nitrates of chromium, copper and potassium onalumina;

b. reacting said paraffin therein at a temperature of from 350 to 500Cand removing from said reaction zone a hydrocarbon mixture rich inorthodialkye benzenes having a total of from eight to 18 carbon atoms inthe alkyl chains and;

c. separating said dialkyl benzenes from other components in the mixtureremoved from said reaction zone.

